Field of the Invention
The present invention relates to an organic light emitting display device, and more particularly to an organic light emitting display device capable of sensing and compensating characteristics of light emitting elements thereof.
Discussion of the Related Art
Image display devices, which render a variety of information on a screen, are core technologies of the information communication age, and are being developed toward improved thinness, lightness, portability, and performance improved. As a result, an organic light emitting display device or the like, which displays an image through an amount of light emitted from an organic light emitting layer, is highlighted as a flat display device capable of eliminating drawbacks of a cathode ray tube (CRT), that is, achieving a reduction in weight and a reduction in volume.
Such an organic light emitting display device includes a plurality of pixels arranged in matrix form, to display an image. In this case, each pixel includes a light emitting element, and a pixel driving circuit including a plurality of transistors to drive the light emitting element in an independent manner.
In organic light emitting display devices according to a related art, however, light emitting elements thereof are degraded with passage of time. That is, as shown in FIG. 1, current-voltage (I-V) characteristics of a light emitting element are degraded with passage of time. As a result, the point of intersection between a characteristic curve of a driving transistor and a characteristic curve of the light emitting element, namely, a driving point, shifts (DP→DP′). This causes generation of a latent image or non-uniformity of luminance. Reduced luminance may cause a reduction in lifespan of the product.
Therefore, an organic light emitting display device capable of sensing and compensating characteristics of light emitting elements thereof is needed.